I will use a model system to investigate the cellular mechanisms that underlie experience-dependent plasticity of neural maps. In the optic tectum of the barn, the auditory space map and visual space map are mutually aligned and integrated, to provide a unified representation of space. If the visual map is displaced by mounting prismatic glasses on young owls, the auditory map shifts in response, restoring the alignment. This form of adaptive plasticity likely involves axonal outgrowth and formation of new circuitry; however, very little is known about the underlying molecular mechanisms. The first goal of this proposal is to characterize the physiological, anatomical and molecular changes that occur during the induction of plasticity. Neurotrophins (NTs) are extracelluar signals that cause axonal outgrowth and synapse stabilization, and in addition NT production is regulated by neuronal activity. Thus, NTs could be the molecular links that trigger adaptive plasticity. To test this, I will manipulate in vivo the activity of neurotrophins and their cognate receptors in developing owls. I will assess the effects of these manipulations on the re-alignment of the auditory and visual space maps by both electrophysiological and anatomical methods. If successful, these experiments will provide important mechanistic insights into the unique capacity of young brains to learn, store and process information.